1. Field of the Invention
The invention relates to defibrillators and, in particular, to a system for permitting the type of electrode connected to the defibrillator to be determined to help ensure that the therapy applied through the defibrillator is appropriate for the type of electrode connected to the patient. The invention also relates to defibrillators and, in particular, to a system for measuring the quality of electrodes prior to being used on a patient.
2. Description of the Prior Art
Sudden cardiac death is the leading cause of death in the United States. Most sudden cardiac death is caused by ventricular fibrillation (xe2x80x9cVFxe2x80x9d), in which the heart""s muscle fibers contract without coordination, thereby interrupting normal blood flow to the body. The only known effective treatment for VF is electrical defibrillation, in which an electrical pulse is applied to a patient""s heart. The electrical shock clears the heart of the abnormal electrical activity (in a process called xe2x80x9cdefibrillationxe2x80x9d) by depolarizing a critical mass of myocardial cells to allow spontaneous organized myocardial depolarization to resume.
The electrical pulse must be delivered within a short time after onset of VF in order for the patient to have any reasonable chance of survival. To be effective, the defibrillation shock must be delivered to the patient within minutes of the onset of VF. Studies have shown that defibrillation shocks delivered within one minute after the onset of VF achieve up to a 100% survival rate. However, the survival rate falls to approximately 30% after only 6 minutes. Beyond 12 minutes, the survival rate approaches zero. Importantly, the more time that passes, the longer the brain is deprived of oxygen and the more likely that brain damage will result. Electrical fibrillation may also be used to treat shockable ventricular tachycardia (xe2x80x9cVTxe2x80x9d). Accordingly, defibrillation is the appropriate therapy for any shockable rhythm, that is, VF or shockable VT.
One way of providing electrical defibrillation uses implantable defibrillators, which are surgically implanted in patients that have a high likelihood of experiencing VF. Implanted defibrillators typically monitor the patient""s heart activity and automatically supply the requisite electrical defibrillation pulses to terminate VF. Implantable defibrillators are expensive, and are used in only a small fraction of the total population at risk for sudden cardiac death.
External defibrillators send electrical pulses to a patient""s heart through electrodes applied to the patient""s torso. External defibrillators are typically located and used in hospital emergency rooms, operating rooms, and emergency medical vehicles. Of the wide variety of external defibrillators currently available, automatic and semi-automatic external defibrillators, collectively referred to as xe2x80x9cAEDsxe2x80x9d, are becoming increasingly popular because relatively inexperienced personnel can use them. U.S. Pat. No. 5,607,454 to Cameron et al., entitled Electrotherapy Method and Apparatus, and PCT publication number WO 94/27674, entitled Defibrillator With Self-Test Features, the specifications of which are hereby incorporated by reference, describe AEDs.
AEDs provide a number of advantages, including the availability of external defibrillation at locations where external defibrillation is not regularly expected, and is likely to be performed quite infrequently, such as in residences, public buildings, businesses, personal vehicles, public transportation vehicles, among other locations. Although operators of AEDs can expect to use an AED only very occasionally, they must nevertheless perform quickly and accurately when called upon. For this reason, AEDs automate many of the steps associated with operating external defibrillation equipment. Along these lines, the operation of AEDs is intended to be simple and intuitive. AEDs are designed to minimize the number of operator decisions required.
Although AEDs were first contemplated to be used for treating adult VF and shockable VT, the present invention provides a solution that can permit AEDs to be utilized to treat pediatric patients. In order to minimize cost and simplify their use, AEDs often include only one connector for connecting electrodes. There are situations where the operator would like to use the AED as a low cost ECG monitor. The present invention can provide a means to connect and detect monitoring electrodes through the same connector used for defibrillation electrodes. The present invention can also provide the ability to monitor the condition of each electrode individually in a sealed package while connected to a defibrillator. The present invention can, therefore, permit the condition of an electrode to be monitored when each electrode is sealed in its a package.
To provide these and other advantages, the present invention provides a system for identifying electrodes connected to a defibrillator. The system includes at least one connecting pin operatively connected to an electrode. Each connecting pin includes at least one pair of contacts. A receptacle receives each connecting pin. Circuitry is operatively connected to the receptacle for detecting shorting of the contacts to determine a type of electrode connected to the receptacle.
The present invention also provides a method for determining a type of electrode attached to a defibrillator. According to the method, connecting pins operatively connected to the electrodes are inserted into a receptacle for receiving the connecting pins. It is determined whether any shorts exist between contacts on the pins and a pattern of shorts to determine the electrode type.
Still other objects and advantages of the present invention will become readily apparent by those skilled in the art from a review of the following detailed description. The detailed description shows and describes preferred embodiments of the invention, simply by way of illustration of the best mode contemplated of carrying out the present invention. As will be realized, the invention is capable of other and different embodiments and its several details are capable of modifications in various obvious respects, without departing from the invention. Accordingly, the drawings and description are illustrative in nature and not restrictive.